1. Field of the Invention
The present invention relates to a method of fabricating a liquid crystal display (LCD) device, and more particularly, to a method of curing a seal pattern for an LCD device.
2. Discussion of the Related Art
As information age progresses, flat panel display (FPD) devices having the characteristics of light weight, thin profile, and low power consumption have developed. Specifically, liquid crystal display (LCD) devices have been widely used for a notebook computer, a monitor and a television because of their superiority in resolution, color display and display quality.
In general, the LCD device includes a liquid crystal panel that has two substrates facing and spaced apart from each other and a liquid crystal layer between the two substrates. The LCD device further includes electrodes on the two substrates for providing an electric field between the two substrates. The electric field generated between the electrodes aligns liquid crystal molecules of the liquid crystal layer, thereby displaying an image by changing light transmittance.
The LCD device is fabricated through an array process for forming an array substrate and a color filter substrate, a cell process for forming a liquid crystal panel, and a module process for integrating the liquid crystal panel and a backlight unit. In the array process, an array layer and a color filter layer are formed on the array substrate and the color filter substrate, respectively, through repetition of a thin film deposition, a photolithography and an etching. In the cell process, the array substrate and the color filter substrate are attached using a seal pattern and the liquid crystal layer is formed between the array substrate and the color filter substrate to complete the liquid crystal panel. In the module process, a polarizing plate and a driving circuit are attached to the liquid crystal panel and the backlight unit is integrated with the liquid crystal panel to complete the LCD device.
In the cell process, the seal pattern provides a gap between the array substrate and the color filter substrate for injecting a liquid crystal material and prevents the leakage of the injected liquid crystal material. The seal pattern may be formed of a sealant including one of a heat-curable resin capable of being cured with a heat and a UV (ultraviolet)-curable resin capable of being cured with a UV ray. The UV-curable resin having a superior adhesion property in low temperature to the heat-curable resin has been widely used.
The UV-curable resin includes a photoinitiator, a monomer having a UV-curing agent and a glass fiber for keeping a cell gap. After the seal pattern is formed on one of the two substrates, the liquid crystal layer is formed between the two substrates and the seal pattern is cured with a UV ray from a mercury lamp or a metal halide lamp to form the seal pattern.
Recently, according to the request for a high response speed of the LCD device, a liquid crystal material for the high response speed has been developed. The liquid crystal material for the high response speed includes a photoinitiator and a monomer, and the photoinitiator of the liquid crystal material reacts to a UV ray so that the liquid crystal material can be stabilized. However, since the UV ray for curing the seal pattern has intensity greater than the UV ray for stabilizing the liquid crystal layer, the photoinitiator of the liquid crystal layer reacts to the UV ray when the UV ray is irradiated for curing the seal pattern. As a result, the liquid crystal layer is partially over-cured and deteriorated.
Although an additional mask is used for preventing irradiation of the UV ray for curing the seal pattern onto the liquid crystal layer having the photoinitiator, the additional mask does not completely block the UV ray onto the liquid crystal layer in a region adjacent to the seal pattern and the liquid crystal layer in the region adjacent to the seal pattern is deteriorated by the UV ray.
FIGS. 1A and 1B are views showing a light leakage and a stain, respectively, of an LCD device according to the related art. In FIG. 1A, the LCD device has a light leakage in a region adjacent to a seal pattern. Alternatively, in FIG. 1B, the LCD device has a stain corresponding to the UV curing apparatus. Accordingly, the display quality of the LCD device is reduced due to the light leakage and the stain. In addition, the fabrication cost of the LCD device increases due to the additional mask.